Interpretive Summary: Broad-leaved dock is amongst the most invasive weeds on arable lands and pastures, and causes detrimental effects on the agricultural production. This plant is known to accumulate a compound called oxalate in leaves. Plants often utilize oxalate for aluminum tolerance, but it is largely unknown how the level of aluminum impacts the formation of oxalate and related compounds against aluminum toxicity. This study first quantified oxalate and other important biochemicals produced by broad-leaved dock under aluminum stress. Statistical analyses of the results indicated organ-specific up-regulation of oxalate (and other biochemicals) formation under aluminum stress.

Technical Abstract:
In this study we analyzed metabolite alterations induced by aluminum (Al) stress in Rumex species using the capillary electrophoresis mass spectrometry. Comprehensive metabolome analysis revealed that oxalate and its precursors were up-regulated in leaves of R. obtusifolius by Al3+. Unlike leaves, citrate contents were increased by Al3+ in stems. Comparison of metabolite profiles among three Rumex species grown under Al3+ showed that oxalate up-regulation was commonly observed in each Rumex species. However, multivariate analyses revealed the differences of metabolite levels among R. obtusifolius and other two Rumex species, which reflected the aluminum tolerance level in acidic condition.